Veg IPM Update: Week Ending 8/03/16

Sweet Corn

European corn borer (ECB) adult activity is stable at very low levels Areas of highest activity are in central Morris County (see ECB map). As always, consider treating when the number of infested plants in a 50 plant sample exceeds 12%. Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays. See the 2016 Commercial Vegetable Recommendations Guide for insecticide choices.

The highest nightly ECB catches for the previous week are as follows:

Allentown 1

Lawrenceville 1

Cinnaminson 1

Long Valley 1

Denville 1

Princeton 1

Eldora 1

Fall armyworm (FAW) infestations are continue throughout NJ, with infestation rates in the 30% range in coastal areas from Cape May through the central counties. Lower numbers have been found inland, but FAW is present in all counties at this time. This pest can be devastating to small corn plants. Fields down to seedling stage should be scouted weekly for signs of infestation. Treat when FAW alone or in combination with ECB damage exceeds 12% plants infested. FAW do not respond well to pyrethroid insecticides. The most useful products are those in the IRAC group 28 class (Coragen, Exirel, Belt) or the IRAC group 5 class (Radiant, Entrust), or combination products including these classes. See the 2016 Commercial Vegetable Recommendations Guide for insecticides effective against FAW.

Corn earworm moth (CEW) activity is gradually increasing, mainly in the southern third of the state. Blacklight traps further north in the state have registered only scattered individuals. Overall activity is fairly low for this time of year, and is mainly from the Delaware Bay shore east to the coast in southern NJ (see CEW Map). Catches in DE are still low, but trap catches published from North Carolina have increased over the past 2 weeks. We should expect increasing populations in NJ over the next several weeks. Large, rapid increases will be dependent on the assistance of low pressure systems.

The highest nightly CEW catches for the previous week are as follows:

East Vineland 4

Denville 1

Jones Island 1

Allentown 1

Eldora 1

Pedricktown 1

Beckett 1

Folsom 1

Tabernacle 1

Centerton 1

Green Creek 1

Woodstown 1

The limited CEW pheromone trap network in the southern counties is also showing continued increase over the past week. Activity has shifted so that it is highest in central areas of southern NJ (see CEW pheromone map). The low number of traps results in broad areas of color within the map. It is critical that growers monitor local CEW moth numbers. At present, this population constitutes a moderate threat to silking corn.

The highest nightly CEW pheromone trap catches for the previous week are as follows:

Elm 22

Jobstown 10

Springdale 4

Monroeville 15

East Vineland 7

Green Creek 10

Beckett 4

For silking sweet corn, the following spray schedules are warranted.

Silking Spray Schedules*:

South – 3-4 days

Central – 5-6 days

North – 6 days

*These recommendations are based on regional catches.

Brown Marmorated Stinkbug (BMSB)

BMSB numbers increased in southern NJ blacklight traps this past week. The highest activity at this time is along the Delaware Bay Shore, with particularly high catches near the Cumberland-Salem border. BMSB are being captured in all parts of the state, although in much reduced umbers in the north. It is important that host crops like peppers be scouted regularly for the presence of BMSB and other stinkbugs at this time.

The highest nightly BMSB trap catches for the previous week are as follows:

Centerton 14

Crosswicks 7

Matawan 4

Beckett 12

Jones Island 7

Green Creek 3

Woodstown 12

Allentown 4

Georgetown 3

Pedricktown 8

Eldora 4

Lawrenceville 3

Pumpkins and Winter Squash

Powdery mildew(PM) is active on pumpkin and winter squash fields throughout NJ. The action threshold for commencement of the protectant fungicide program for PM is 2 lesions per 100 older leaves. See the 2016 Commercial Vegetable Recommendations Guide for a list of appropriate protectant fungicide rotations for PM control.

To repeat from last week:

A sentinel plot containing susceptible and resistant cucumber varieties, as well as muskmelons, watermelons, acorn and butternut squash and pumpkins is now established at the Snyder Research and Extension Farm in Hunterdon County. The purpose of this plot is to detect the presence of downy mildew (DM) in northern NJ. As of July 27, DM HAS BEEN DETECTED on the susceptible cucumber variety ‘Straight 8’. No other crops in the sentinel plot are infected, including the resistant cucumber variety SV 3462 from Seminis. Rains of this week could make conditions more favorable for disease development, so all growers should be applying appropriate protectant fungicides plus DM specific materials to cucumbers at this time. DM lesions appear as yellow areas on the upper leaf surface with leaf veins making distinct borders to the lesions (see photos above). On the lower leaf surface, beneath the lesions, dark spores may be seen if conditions are moist. For more information on the regional presence of DM as well as comprehensive, weekly forecasts, see the following website: http://cdm.ipmpipe.org/

Peppers and Tomatoes

Stinkbugs are being found in scouted fields with increasing frequency over the past week. These bugs are laying eggs now. As eggs hatch, nymphs ( which cannot fly) will remain clustered together, causing significant local injury to green and ripening fruit. If fruit injury is increasing in harvests, or stinkbug adults, nymphs, or eggmasses are found in more than one of 10 samples in a field, consider treating for this pest to limit injury. See the 2016 Commercial Vegetable Recommendations Guide for insecticides effective against stinkbugs.

Pepper weevil

None have been trapped in the past week at either farms or processing facilities. As far as known, there are no infested fields. We have only another six weeks to be concerned about PW. After mid-September,
infestations will be of little concern.